Denopamine, a beta(1)-adrenergic agonist, increases alveolar fluid clearance in ex vivo rat and guinea pig lungs

The effect of denopamine, a selective beta (1)-adrenergic agonist, on alveo lar fluid clearance was determined in both ex vivo rat and guinea pig lungs . Alveolar fluid clearance was measured by the progressive increase in the concentration of Evans blue-labeled albumin over 1 h at 37 degreesC. Denopa mine (10(-6) to 10(-3) M) increased alveolar fluid clearance in a dose-depe ndent manner in ex vivo rat lungs. Denopamine also stimulated alveolar flui d clearance in guinea pig lungs. Atenolol, a selective beta (1)-adrenergic antagonist, and amiloride, a sodium channel inhibitor, inhibited denopamine -stimulated alveolar fluid clearance. The potency of denopamine was similar to that of similar doses of isoproterenol or terbutaline. Shortterm hypoxi a (100% nitrogen for 1-2 h) did not alter the stimulatory effect of denopam ine. Denopamine (10(-4), 10(-3) M) increased intracellular adenosine 3',5'- cyclic monophosphate levels in cultured rat alveolar type II cells. In summ ary, denopamine, a selective beta (1)-adrenergic agonist, stimulates alveol ar fluid clearance in both ex vivo rat and guinea pig lungs.